I see where your trying to go with this Jaynik, Yes, a persons "taste" of beer is subjective and that's why we have so many diffrent styles and flavors of beer. But your missing a few key points...
The definition of a "good" beer and a "great" beer is not subjective but outlined in the BJCP judging guidelines. Strained yeast give off flavors that a trained palate can detect. While most of us don't judge beer on a regular basis we typically fall into the beers that we like and compare our homebrew to there likeness.
Starters help for quicker fermentation's and the stronger yeast can fight off bacteria before it can become a problem. The quicker a fermentation starts, it betters your chances for the yeast to clean up there own mess and not stress about food consumption.
To each there own, if you are unperturbed about off flavors in your beer, that's your prerogative. But to say that making a starter doesn't "help" to make better beer unsubjectivly is apocryphal.